Polyurea self-repairing material based on dynamic imine bonds as well as preparation method and application of polyurea self-repairing material

Abstract

The invention discloses a polyurea self-repairing material based on dynamic imine bonds and a preparation method and application thereof, and belongs to the technical field of self-repairing insulating paints.The preparation method includes the steps that firstly, poly (dimethyl siloxane), bis (3-aminopropyl) end capping and mixed isocyanate are copolymerized to obtain an IH-PDMS precursor solution; then, a dynamic imine bond cross-linked network is constructed through the Schiff base reaction of the IH-PDMS precursor solution and terephthalaldehyde, a polyurea solution is obtained and cured, and the polyurea self-repairing material is obtained. The polyurea self-repairing material has high insulation performance, the breakdown strength of the optimized polyurea self-repairing material reaches 43.89 kV / mm, the optimized polyurea self-repairing material completely meets the technical standard of local insulation of the transmission tower, the optimized polyurea self-repairing material has excellent mechanical and thermal stability, the tensile strength reaches 13.87 MPa, and the static contact angle is gt; no thermal weight loss exists at the temperature of 100 DEG C and below 240 DEG C, and the coating adapts to extreme environments such as high temperature.

Description

Technical Field

[0001] The present invention belongs to the technical field of self-repairing insulating coatings, and in particular relates to a polyurea self-repairing material based on a dynamic imine bond, and a preparation method and application thereof. Background Art

[0002] As power system voltage levels increase and operating environments become more complex, local insulation protection technologies for transmission towers face higher requirements. Polyurea-based resins, due to their unique molecular structure, exhibit excellent mechanical strength, chemical resistance, and rapid curing properties. They also possess significant potential for self-healing and modification, demonstrating significant advantages in insulating key tower components (such as hardware connections and grounding down conductors). In recent years, self-healing polyurea materials have become a research hotspot in the insulation materials field due to their unique dynamically reversible chemical bonds and excellent mechanical properties.

[0003] Existing research mainly focuses on optimizing the physical and mechanical properties of materials and improving their self-healing efficiency, and has made significant progress in molecular structure design and selection of dynamic bond types (such as hydrogen bonds, Diels-Alder bonds, disulfide bonds, etc.). However, research in this field has obvious limitations: First, the current self-healing system requires harsh conditions such as high temperature (usually >80°C), long-term treatment (several hours), or specific stimulus sources (such as ultraviolet light) to trigger the repair function, which makes it difficult to meet the needs of rapid self-repair of power equipment at room temperature and in complex field environments. There are large gaps in existing research on the electrical properties of self-healing polyurea materials: on the one hand, the structural evolution law of the dynamic cross-linking network under the action of an electric field and its influence mechanism on carrier transport are still unclear, resulting in doubts about the reliability of the material under long-term electric field action; on the other hand, there is a lack of systematic research on the key electrical parameters of self-healing polyurea materials (such as dielectric strength recovery rate and volume resistivity change), which restricts its application verification in high-voltage insulation scenarios.

[0004] When intact, polyurea exhibits excellent insulation performance and physical and chemical stability. Its dielectric strength, weather resistance, and mechanical properties meet the technical requirements for localized insulation on transmission towers. However, this material has significant drawbacks in practical applications: when damaged by external forces, its insulation performance and mechanical integrity deteriorate dramatically. More critically, traditional polyurea lacks self-healing capabilities and cannot autonomously restore the insulation performance of damaged areas, posing a direct threat to the operational safety of power equipment. Existing maintenance methods have multiple drawbacks. First, damaged material must be repaired using a secondary recoating process, which not only requires specialized spray equipment but also places strict demands on ambient temperature, humidity, and substrate surface preparation. Second, recoating involves multiple steps, including surface preparation, layered repairs, and curing and maintenance, making it complex and time-consuming. Furthermore, since transmission towers are often located in complex outdoor environments, working at height is difficult, significantly increasing repair costs (including equipment transportation, labor, and power outage losses). This passive maintenance model not only significantly increases the operation and maintenance costs of power systems, but also can lead to the expansion of insulation defects due to delayed repairs, which can in turn cause serious accidents such as breakdown and discharge. To address these technical bottlenecks, there is an urgent need to develop a new type of self-healing polyurea material. Summary of the Invention

[0005] To solve the above technical problems, the present invention proposes a polyurea self-healing material based on dynamic imine bonds, its preparation method and application. The polyurea self-healing material has a dual reversible dynamic bond cross-linked network structure based on imine bonds and hydrogen bonds, which gives the material good self-healing ability and excellent thermodynamic and electrical properties, fully meeting the local insulation requirements of transmission towers.

[0006] To achieve the above objectives, the present invention provides a method for preparing a polyurea self-healing material based on a dynamic imine bond, comprising:

[0007] First, IH-PDMS precursor solution was obtained by copolymerization of poly(dimethylsiloxane), bis(3-aminopropyl) end-capping and mixed isocyanate;

[0008] Then, a dynamic imine bond cross-linking network is constructed by reacting the IH-PDMS precursor solution with a Schiff base of terephthalaldehyde to obtain an imine bond cross-linked polyurea solution, which is then cured to obtain the dynamic imine bond-based polyurea self-healing material.

[0009] Furthermore, the mixed isocyanate consists of isophorone diisocyanate and hexamethylene diisocyanate.

[0010] Furthermore, the molar ratio of isophorone diisocyanate to hexamethylene diisocyanate is x:y, wherein 0<x<10, y=10-x.

[0011] Furthermore, in the method of constructing a dynamic imine bond cross-linked network by reacting the IH-PDMS precursor solution with a Schiff base of terephthalaldehyde, trimethylolpropane tripropylene glycol ether (amino terminated) is also added; the molar ratio of the poly(dimethylsiloxane), bis(3-aminopropyl) terminated to the trimethylolpropane tripropylene glycol ether (amino terminated) is 70:1.

[0012] Furthermore, the molar ratio of the poly(dimethylsiloxane) end-capping agent and the terephthalaldehyde is 10.5:1.73.

[0013] Furthermore, the method for obtaining an IH-PDMS precursor solution by copolymerizing poly(dimethylsiloxane), bis(3-aminopropyl) end-capping and mixed isocyanate comprises:

[0014] Under nitrogen protection, isophorone diisocyanate and hexamethylene diisocyanate are dissolved in tetrahydrofuran and stirred evenly; poly(dimethylsiloxane) end-capped with bis(3-aminopropyl) is dissolved in tetrahydrofuran and added dropwise to the mixed solution containing isophorone diisocyanate and hexamethylene diisocyanate; after the addition is completed, the mixture is stirred evenly and reacted to obtain an IH-PDMS precursor solution.

[0015] Furthermore, the method for constructing a dynamic imine bond cross-linked network by reacting the IH-PDMS precursor solution with a Schiff base of terephthalaldehyde comprises:

[0016] Under nitrogen protection, trimethylolpropane tripropylene glycol ether (amino terminated) was added dropwise to the IH-PDMS precursor solution and stirred to mix evenly; then terephthalaldehyde was added and glacial acetic acid was added dropwise as a catalyst to react to obtain an imine bond cross-linked polyurea solution.

[0017] Furthermore, the curing conditions include curing at 60° C. under vacuum conditions for 6 hours and post-curing at 50° C. for 2 hours.

[0018] The present invention also provides a polyurea self-repairing material based on a dynamic imine bond, which is prepared according to the above-mentioned method for preparing the polyurea self-repairing material based on a dynamic imine bond.

[0019] The present invention also provides an application of the above-mentioned polyurea self-repairing material based on dynamic imine bonds, wherein the polyurea self-repairing material based on dynamic imine bonds is applied to local insulation protection of transmission towers.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects:

[0021] This invention introduces a dual reversible crosslinking network of dynamic imine bonds and hydrogen bonds into the polyurea material. Through the synergistic effect of these bonds, the material is endowed with the ability to rapidly self-repair at low temperatures (50°C) (complete repair within 180 minutes). This overcomes the inability of traditional polyurea materials to autonomously repair damage, significantly reduces repair energy consumption, and is suitable for the complex outdoor environments of transmission towers. Through the molecular design of dynamic bonds, the material achieves both high insulation performance (breakdown strength ≥ 39.84 kV / mm) and self-repair capabilities, overcoming the limitations of existing self-repairing materials, which rely on harsh external stimuli such as high temperatures (>80°C) or ultraviolet light.

[0022] By introducing a mixed isocyanate and exploring a ratio of IPDI to HDI (e.g., IPDI:HDI = 6:4), this paper experimentally verified the optimal self-healing material with the best overall performance (tensile strength of 13.87 MPa, static contact angle of 102.37°, and breakdown strength of 43.89 kV / mm), addressing the performance imbalance of single-component materials. Furthermore, by adjusting the IPDI content and optimizing the material's microscopic roughness (SEM verification of controllable roughness), the material's hydrophobicity was enhanced without compromising repair efficiency.

[0023] The present invention adopts a step-by-step synthesis and low-temperature curing process, adopts nitrogen protection and staged reaction (prepolymer preparation → imine bond cross-linking → vacuum curing) to ensure the stable formation of dynamic bonds, and adjusts process parameters (such as reaction temperature of 80°C and nitrogen protection), thereby significantly improving the thermal stability of the material (no thermal weight loss within 240°C) and avoiding performance degradation caused by traditional high-temperature curing.

[0024] The polyurea self-healing material of this invention possesses high insulation properties. The optimized material achieves a breakdown strength of 43.89 kV / mm, far exceeding commercial polyurea materials (typically <25 kV / mm) and fully meeting the technical standards for local insulation of transmission towers. It also exhibits excellent mechanical and thermal stability, with a tensile strength of 13.87 MPa, a static contact angle >100° (excellent hydrophobicity), and no thermal weight loss below 240°C, making it suitable for extreme environments such as high temperatures.

[0025] This invention addresses the requirements for high hydrophobicity, high weather resistance, and rapid repair of localized insulation on transmission towers. It optimizes the material's surface morphology, enabling long-term, stable service in complex field environments. This is the first systematic study of the influence of dynamic cross-linking structure on the electrical properties of polyurea materials, filling a technological gap in this field. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 For different resin systems PU-I x H y -T surface micromorphology; among them, Figure 1 (a) is PU-I with IPDI:HDI=x:y=0:10 x H y -T surface micromorphology, Figure 1 (b) is PU-I with IPDI:HDI=x:y=2:8 x H y -T surface micromorphology, Figure 1 (c) is PU-I with IPDI:HDI=x:y=4:6 x H y -T surface micromorphology, Figure 1 (d) is PU-I with IPDI:HDI=x:y=6:4 x H y -T surface micromorphology, Figure 1 (e) is PU-I with IPDI:HDI=x:y=8:2 x H y -T surface micromorphology, Figure 1 (f) is PU-I with IPDI:HDI=x:y=10:0 x H y -T surface micromorphology;

[0028] Figure 2 For different resin systems PU-I x H y -Static contact angle results under T water conditions;

[0029] Figure 3 For different resin systems PU-I x H y -Static contact angle results under T-ethylene glycol conditions;

[0030] Figure 4 For different resin systems PU-I x H y -T surface energy, dispersed surface energy and polar surface energy comparison chart;

[0031] Figure 5For different resin systems PU-I x H y -T tensile strength result diagram;

[0032] Figure 6 For different resin systems PU-I x H y -T DSC test result diagram;

[0033] Figure 7 PU-I under different resin systems x H y -T breakdown strength Weibull distribution diagram;

[0034] Figure 8 For different resin systems PU-I x H y -T dielectric constant ε r picture;

[0035] Figure 9 For different resin systems PU-I x H y -T dielectric loss ta nδ diagram;

[0036] Figure 10 For different resin systems PU-I x H y -T self-repair effect diagram, where Figure 10 (a) is PU-I with IPDI:HDI=x:y=0:10 x H y -T self-repair effect diagram, Figure 10 (b) is PU-I with IPDI:HDI=x:y=2:8 x H y -T self-repair effect diagram, Figure 10 (c) is PU-I with IPDI:HDI=x:y=4:6 x H y -T self-repair effect diagram, Figure 10 (d) is PU-I with IPDI:HDI=x:y=6:4 x H y -T self-repair effect diagram, Figure 10 (e) is PU-I with IPDI:HDI=x:y=8:2 x H y -T self-repair effect diagram, Figure 10 (f) is PU-I with IPDI:HDI=x:y=10:0 x H y -T self-repair effect diagram. DETAILED DESCRIPTION

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0039] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0040] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0041] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0042] The main chemical substances involved in the following examples are:

[0043] Isocyanate: isophorone diisocyanate (IPDI, purity 99%), hexamethylene diisocyanate (HDI, purity 99%).

[0044] Amine compounds: poly (dimethylsiloxane), bis (3-aminopropyl) end-capped (NH2-PDMS-NH2, number average molecular weight M n ≈1000), trimethylolpropane tripropylene glycol ether (amino terminated) (T-403, number average molecular weight ).

[0045] Aldehyde compounds: terephthalaldehyde (TA, purity 98%).

[0046] Solvent: tetrahydrofuran (THF, purity 99%).

[0047] All chemicals were of analytical grade and used without further purification.

[0048] Example 1

[0049] The preparation method of a polyurea self-healing material based on a dynamic imine bond comprises the following steps:

[0050] (1) Synthesis of NH2-PDMS-NH2-terminated prepolymer

[0051] 6 mmol IPDI and 4 mmol HDI were dissolved in 15 mL THF, added to a three-necked flask and stirred.

[0052] 10.5 mmol NH2-PDMS-NH2 was dissolved in 20 mL THF and added dropwise to the mixture containing IPDI and HDI through a constant pressure dropping funnel. The addition time was about 1 h.

[0053] After the dropwise addition was completed, the mixture was stirred evenly and reacted at 5° C. for 1 h, and then continued to react at room temperature (25° C.) for 12 h to obtain an IH-PDMS precursor solution.

[0054] The above reactions were all carried out under nitrogen protection to avoid the influence of moisture and air components on the reactions.

[0055] (2) Synthesis of imine bond cross-linked polyurea materials

[0056] 0.15 mmol of T-403 was added dropwise to the IH-PDMS precursor solution and stirred to mix evenly.

[0057] Then, 30 mL of a THF solution containing 1.73 mmol of TA was added, and a few drops of glacial acetic acid (1.5 mmol) were added dropwise as a catalyst.

[0058] The reaction was carried out at 80° C. for 12 h to obtain an imine bond cross-linked polyurea solution.

[0059] The above reactions were all carried out under nitrogen protection to avoid the influence of moisture and air components on the reactions.

[0060] (3) Material curing and molding

[0061] The polyurea solution was poured into a polytetrafluoroethylene mold and placed in a vacuum drying oven at 60°C for 6 hours. Then, it was transferred to a blast drying oven and post-cured at 50°C for 2 hours. After cooling to room temperature, a polyurea self-healing material PU-I based on dynamic imine bonds was obtained. x H y -T(PU-I6H4-T, IPDI:HDI=x:y=6:4).

[0062] Example 2

[0063] The only difference from Example 1 is that the amounts of IPDI and HDI used are 0 mmol and 10 mmol respectively.

[0064] Example 3

[0065] The only difference from Example 1 is that the amounts of IPDI and HDI used are 2 mmol and 8 mmol respectively.

[0066] Example 4

[0067] The only difference from Example 1 is that the amounts of IPDI and HDI used are 4 mmol and 6 mmol respectively.

[0068] Example 5

[0069] The only difference from Example 1 is that the amounts of IPDI and HDI used are 8 mmol and 2 mmol respectively.

[0070] Example 6

[0071] The only difference from Example 1 is that the amounts of IPDI and HDI used are 10 mmol and 0 mmol respectively.

[0072] Test case performance test

[0073] (1) Micromorphology (SEM)

[0074] Scanning electron microscopy (SEM) is a common method for characterizing the microscopic morphology of materials. The surface morphology of the polyurea material was photographed using a scanning electron microscope (Thermo Fisher Scientific Nova NanoSEM 450). During the test, a film sample of appropriate size was fixed to the test platform with conductive adhesive and gold was sprayed on its surface. The electron beam acceleration voltage was set to 5.00 kV.

[0075] The polyurea self-repairing materials obtained in Examples 1-6 were subjected to SEM testing, and the results were as follows: Figure 1 As shown in the figure, with the increase of IPDI addition, the microscopic morphology of the material surface gradually changes from a smooth state to a relatively rough state. For hydrophobic materials, increasing roughness is beneficial to improving the hydrophobicity of the hydrophobic material, but it is not conducive to repairing surface damage.

[0076] (2) Static contact angle under water and ethylene glycol conditions

[0077] The surface properties of the material were characterized by surface energy. A contact angle meter (JC2000DM, Shanghai Zhongchen) was used. Deionized water and ethylene glycol were selected as titration liquids. Five different points on the sample were selected for the experiment. The liquid contact angle was captured and saved after 10 seconds. The static contact angles (θ) were measured and the average static contact angle was calculated.

[0078] According to the contact angles of deionized water and ethylene glycol on the surface of polyurea material, the surface energy of the material can be calculated by formulas (1)-(3).

[0079]

[0080] Where, γ s 、 and are the surface energy, dispersed surface energy, and polar surface energy of different films respectively; γ L 、 and The surface energy of the titration liquid, the dispersed surface energy and the polar surface energy are respectively: θ is the contact angle of different films. Deionized water and ethylene glycol are selected as the titration liquids for measurement. Their dispersed surface energy is 21.8mJ / m 2 、29.3mJ / m 2 , polar surface energy 51.0mJ / m 2 、19.0mJ / m 2 .

[0081] The static contact angle test of the polyurea self-repairing materials obtained in Examples 1-6 was carried out, and the results were as follows: Figure 2 and Figure 3 As shown in the figure, when the titration liquid is deionized water, the static contact angle tends to increase slightly with increasing IPDI addition at different IPDI / HDI ratios. The static contact angle values are all greater than 100°, and the wettability is poor, indicating that the material is a good hydrophobic material. Increasing the amount of IPDI added helps reduce the adsorption of water molecules and improves the wettability of the material surface.

[0082] like Figure 4 As shown, the polar surface energy The material's surface energy is significantly affected by the isocyanate ratio, with a distribution range of 4.24 to 8.93 mN / m. The dispersed surface energy shows a trend of first increasing, then decreasing, and then increasing again, with a distribution range of 8.69 to 20.38 mN / m. The surface energy of the material is significantly affected by the dispersed surface energy, and the surface energy variation trend is consistent with that of the dispersed surface energy. The calculated surface energy range indicates that the material exhibits good hydrophobicity, which is attributed to the fact that the introduction of silicone not only directly increases the material's hydrophobicity but also indirectly reduces it through the formation of a hydrophobic layer via a cross-linking reaction.

[0083] (3) Tensile properties

[0084] The tensile strength test of polyurea materials was carried out at room temperature using a universal tensile testing machine (BOS-100KNW, China). The loading rate was set at 50 mm / min. -1 , each dumbbell-shaped sample was tested 3 times and the average value was taken.

[0085] The tensile properties of the polyurea self-repairing materials obtained in Examples 1-6 were tested, and the results were as follows: Figure 5 As shown in the figure, as the IPDI addition ratio increases, the tensile strength of the material shows a trend of first increasing and then decreasing. When the IPDI:HDI ratio is 4:6, the material shows the optimal tensile strength of 15.24 MPa. Too high or too low an IPDI addition ratio will reduce the tensile strength of the polyurea material, which is not conducive to improving the overall performance of the polyurea material.

[0086] (4)DSC performance

[0087] Differential Scanning Calorimetry (DSC) test: A differential scanning calorimeter (NETZSCH DSC 3500Sirius, NETZSCH, Germany) was used to study the thermal properties of the samples. 5-10 mg of sample was weighed and placed in a perforated aluminum crucible. During the DSC test, a N2 atmosphere with a flow rate of 20 mL / min was opened, the heating rate β was set to 20 K / min, the starting temperature was 20°C, and the ending temperature was 450°C.

[0088] The polyurea self-repairing materials obtained in Examples 1-6 were subjected to DSC tests, and the results were as follows: Figure 6 As shown in the figure, each polyurea material sample did not show obvious endothermic or exothermic peak before 240°C, indicating that the polyurea samples with different IPDI and HDI addition ratios all have good thermal stability and meet the application requirements in the field of local insulation of transmission towers.

[0089] (5) Breakdown strength

[0090] The power frequency breakdown voltage test measures the breakdown strength of samples subjected to an alternating electric field at a voltage ramp rate of 2 kV / s, according to the IEC 60243-1:2013 test standard. Block samples measure 50 mm × 50 mm × 1 mm, with a voltage ramp rate of 2 kV / s. The test environment is room temperature, and the test electrodes are spherical electrodes with a diameter of 20 mm. Each sample is subjected to five breakdown tests at different locations, and the breakdown voltage data is analyzed using the Weibull distribution function.

[0091] The polyurea self-repairing materials obtained in Examples 1-6 were subjected to breakdown strength tests, and the results were as follows: Figure 7 As shown in the figure, the characteristic breakdown strengths at different IPDI to HDI ratios are 51.18 kV / mm, 48.07 kV / mm, 39.84 kV / mm, 43.89 kV / mm, 46.62 kV / mm, and 50.25 kV / mm, respectively. As the amount of IPDI added increases, the breakdown strength first decreases and then increases. When the IPDI:HDI ratio is 6:4, the breakdown strength is 39.84 kV / mm, which is the lowest at this time, but still meets the insulation requirements of the solid dielectric required for the transmission tower gap.

[0092] (6) Dielectric properties

[0093] The dielectric constant ε and dielectric loss tanδ were measured on a broadband dielectric impedance spectrometer (Agilent-4294A, USA) at a temperature of 20°C and a frequency range of 40 Hz to 2 MHz. The sample size was 10 mm × 10 mm × 0.3 mm, and silver electrodes were used as the plating electrodes.

[0094] The dielectric properties of the polyurea self-repairing materials obtained in Examples 1-6 were tested, and the results were as follows: Figure 8 and Figure 9 As shown, the relative dielectric constant ε of all samples r Both the dielectric loss tanδ decrease and stabilize with increasing frequency, primarily due to relaxation behavior. With increasing IPDI addition levels, the tanδ of each sample decreases overall at 50 Hz, ranging from 0.37% to 0.21%. These samples exhibit low dielectric constants and dielectric losses, resulting in minimal heating and polarization in electrical applications, fully meeting the requirements for electrical applications.

[0095] (7) Self-repair performance

[0096] The material sample was cut with a scalpel, and the damaged end was immersed in water for 30 seconds. Then, the sample was placed in an oven at 50°C with full contact. The scratch change process of the sample was observed every 45 minutes using an optical microscope (MHZ201 microscope and E3ISPM20000KPA microscope camera, China).

[0097] The self-repairing performance of the polyurea self-repairing materials obtained in Examples 1-6 was tested, and the results were as follows: Figure 10 As shown in the figure, when the IPDI or HDI addition level is zero, the polyurea material does not undergo significant self-healing after 225 minutes at 50°C, and the scratch healing is not very effective. However, polyurea materials with other addition ratios all achieve self-healing within 180 minutes at 50°C. Therefore, excessive IPDI or HDI addition levels are not conducive to the self-healing of polyurea materials.

[0098] In summary, the polymer prepared by the present invention has a dual reversible dynamic bond cross-linked network structure based on imine bonds and hydrogen bonds, and has excellent thermodynamic and electrical properties. When IPDI:HDI=6:4, PU-I6H4-T exhibits the best comprehensive performance, its static contact angle can reach 102.37°, the material does not undergo thermal weight loss within 0-250°C, the mechanical strength is 13.87 MPa, it has excellent hydrophobicity and thermodynamic properties, and the breakdown strength can reach 43.89 kV / mm, which fully meets the local insulation requirements of transmission towers.

[0099] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a polyurea self-healing material based on a dynamic imine bond, characterized in that: include: First, IH-PDMS precursor solution was obtained by copolymerization of poly(dimethylsiloxane), bis(3-aminopropyl) end-capping and mixed isocyanate; Then, a dynamic imine bond cross-linking network is constructed by reacting the IH-PDMS precursor solution with a Schiff base of terephthalaldehyde to obtain an imine bond cross-linked polyurea solution, which is then cured to obtain the dynamic imine bond-based polyurea self-healing material.

2. The method for preparing a polyurea self-healing material based on a dynamic imine bond according to claim 1, characterized in that: The mixed isocyanate consists of isophorone diisocyanate and hexamethylene diisocyanate.

3. The method for preparing a polyurea self-healing material based on a dynamic imine bond according to claim 2, characterized in that: The molar ratio of isophorone diisocyanate to hexamethylene diisocyanate is x:y, wherein 0<x<10, and y=10-x.

4. The method for preparing a polyurea self-healing material based on a dynamic imine bond according to claim 1, characterized in that: In the method for constructing a dynamic imine bond cross-linked network by reacting the IH-PDMS precursor solution with a Schiff base of terephthalaldehyde, trimethylolpropane tripropylene glycol ether (amino terminated) is further added; the molar ratio of the poly(dimethylsiloxane) bis(3-aminopropyl) terminated to the trimethylolpropane tripropylene glycol ether (amino terminated) is 70:

1.

5. The method for preparing a polyurea self-healing material based on a dynamic imine bond according to claim 1, characterized in that: The molar ratio of the poly(dimethylsiloxane) end-capped with bis(3-aminopropyl) to the terephthalaldehyde is 10.5:1.

73.

6. The method for preparing a polyurea self-healing material based on a dynamic imine bond according to any one of claims 1 to 5, characterized in that: The method for obtaining an IH-PDMS precursor solution by copolymerizing poly(dimethylsiloxane), bis(3-aminopropyl) end-capping and mixed isocyanate comprises: Under nitrogen protection, isophorone diisocyanate and hexamethylene diisocyanate are dissolved in tetrahydrofuran and stirred evenly; poly(dimethylsiloxane) end-capped with bis(3-aminopropyl) is dissolved in tetrahydrofuran and added dropwise to the mixed solution containing isophorone diisocyanate and hexamethylene diisocyanate; after the addition is completed, the mixture is stirred evenly and reacted to obtain an IH-PDMS precursor solution.

7. The method for preparing a polyurea self-healing material based on a dynamic imine bond according to any one of claims 1 to 5, characterized in that: The method for constructing a dynamic imine bond cross-linked network through a Schiff base reaction of the IH-PDMS precursor solution and terephthalaldehyde comprises: Under nitrogen protection, trimethylolpropane tripropylene glycol ether (amino terminated) was added dropwise to the IH-PDMS precursor solution and stirred to mix evenly; then terephthalaldehyde was added and glacial acetic acid was added dropwise as a catalyst to react to obtain an imine bond cross-linked polyurea solution.

8. The method for preparing a polyurea self-healing material based on a dynamic imine bond according to any one of claims 1 to 5, characterized in that: The curing conditions include curing at 60° C. under vacuum conditions for 6 hours and post-curing at 50° C. for 2 hours.

9. A polyurea self-healing material based on dynamic imine bonds, characterized in that: The polyurea self-healing material is prepared according to the preparation method of any one of claims 1 to 8.

10. An application of the polyurea self-healing material based on dynamic imine bonds according to claim 9, characterized in that: The polyurea self-repairing material based on dynamic imine bonds is applied to local insulation protection of transmission towers.

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